Final answer:
Less chance of injury in a vehicle crash with an air bag is provided by extending the time over which the collision occurs, thereby reducing the force exerted on passengers through the concept of impulse.
Step-by-step explanation:
The method that provides less chance of injury in a crash when a vehicle is equipped with an air bag involves understanding the concept of impulse. Impulse, Fnet Δt, describes the change in momentum of an object which is equal to the product of the average net force acting on the object and the time interval over which it acts. The deployment of airbags increases the collision time, which in turn, reduces the net force during the collision. This reduction in force lessens the risk of injuries to passengers.
Let's say, for example, during a collision, an airbag deploys and increases the time over which the occupant's momentum changes from the pre-collision state to a complete stop (Δt is increased). This extended time results in a lower average force being exerted on the occupant compared to the scenario without an airbag. Hence, by rearranging the impulse equation to Fnet = Δp/Δt, it's clear that as Δt increases while Δp (momentum change) remains the same, the resulting Fnet (net force) will decrease.
Additionally, modern vehicles incorporate plastic components and design elements that allow the car to crumple upon impact, lengthening the collision time even further, thus providing a safer environment for occupants. This principle has significantly reduced fatalities in racing as well as everyday vehicular accidents by lowering the forces exerted on passengers and, therefore, reducing the likelihood of injury.